- Serena Williams named Sports Illustrated's Sportsperson of the Year for 2015
- But Williams' victory has irked those who think American Pharoah should win
- Thoroughbred horse won coveted Triple Crown and won SI readers' poll vote
(CNN)It was supposed to be a landmark moment in Serena Williams' stellar career: Being crowned Sports Illustrated's Sportsperson of the Year.
But the somewhat begrudging reaction to the 34-year-old's accolade bears witness to America's complicated attitude towards gender and racial equality, according to one horse racing expert.
Williams became the first black woman to win the prestigious award after trumping an unlikely rival to the prize -- thoroughbred racehorse American Pharoah.
Both have an impressive pedigree in 2015.
A 21-time grand slam winner, Williams lost just three of 53 matches, winning three major titles, while American Pharoah won the hallowed American Triple Crown series and the Breeders' Cup title.
But there is simmering resentment that despite attracting 47% of the vote in a SI's readers' poll on who should win, Ahmed Zayat's colt was overlooked for the award itself.